I couldn't make this one up - somebody wrote a visual novel about the protagonist's girlfriend suddenly turning into a big fluffy white alpaca (if you're not familiar with them, think llama, they're sort of similar)

It's called "PACAPLUS" and they've just released an English version which can befound here (The screenshots are still for the JP version; I don' tknow if the demo is English or not, I haven't checked it yet.)

I guess they figured that since pigeons were a hit with Hatoful Boyfriend, maybe alpacas can be the next big thing?